Spectrum access method and apparatus utilizing same

ABSTRACT

A spectrum access method and an apparatus utilizing same. A spectrum management apparatus includes at least one processor configured to: determine location information and antenna angle information of each of at least one secondary apparatus; in response to a request for accessing an idle spectrum of a primary apparatus, determine, according to the location information and the antenna angle information of each of the at least one secondary apparatus, a secondary apparatus to grant access to the idle spectrum; and provide, to a serving base station of each of the secondary apparatuses having the access granted, the location information and the antenna angle information of all of the secondary apparatuses having the access granted, to enable the serving base station to perform interference alignment preceding.

FIELD

The present disclosure relates to a method and an apparatus forcontrolling spectrum access, and in particular to a spectrum accessmethod based on interference alignment precoding technology and anapparatus using the method.

BACKGROUND

With the rapid development of the information technology andmulti-service wireless network, the demand for broadband wirelessservice increases constantly while spectrum which is non-renewableresource is scarce. According to the existing fixed spectrum allocationstrategy, many spectrums that have been allocated to licensed users areidle in certain time periods, which results in low utility efficiency ofspectrums and large waste of spectrums. With cognitive radio (CR)technology, the utility efficiency of spectrums may be improved, andinsufficiency of spectrum resources may be mitigated. Therefore thecognitive radio (CR) technology becomes research hotspot in the field ofwireless communications.

A device (which is referred to as “secondary device” herein) employingthe cognitive radio technology opportunistically accesses an idlefrequency hand of a licensed user equipment (which is referred to as“primary device” herein) without affecting the normal communication ofthe licensed user equipment, thereby realizing dynamic spectrum accessand improving utility efficiency of spectrums.

Although insufficiency of spectrum resources can be mitigated with thecognitive radio technology, a large number of secondary devicesaccessing the idle frequency band of the primary device may result insignificant interferences among users and frequent changes in networkstatus. In a conventional cognitive multiple-input multiple-output(MIMO) system, information exchange usually requires joint informationexchange between a base station and a user equipment in the cognitivesystem. The efficiency of information exchange is greatly decreased asthe number of the user equipments increases.

In addition, it is also necessary to consider a case where the secondarydevices have different priorities (or Quality of Service (QoS) levels).

SUMMARY

In order to solve the above problem, a method for controlling access toan idle frequency band of a primary device based on interferencealignment preceding technology and an apparatus, using the method areprovided in the present disclosure.

According to an aspect of the present disclosure, a spectrum managementapparatus is provided. The spectrum management apparatus includes one ormore processors configured to: determine position information andantenna angle information of each of one or more secondary devicesdetermine at least one secondary device which is allowed to access anidle portion of spectrum of a primary device based on the positioninformation and the antenna angle information of each secondary device,in response to a request from the secondary device for accessing theidle portion of spectrum; and for each of the at least one secondarydevice which is allowed to access, transmit to a serving base stationserving the secondary device the position information and the antennaangle information of all of the at least one secondary device which isallowed to access for the serving base station to perform interferencealignment precoding.

According to another aspect of the present disclosure, a method forcontrolling spectrum access in a communication system is provided. Themethod includes: determining position information and antenna angleinformation of each of one or more secondary devices; determining atleast one secondary device which is allowed to access an idle portion ofspectrum of a primary device based on the position information and theantenna angle information of each secondary device, in response to arequest from the secondary device for accessing the idle portion ofspectrum; and for each of the at least one secondary device which isallowed to access, transmitting to a serving base station serving thesecondary device the position, information and the antenna angleinformation of all of the at least one secondary device which is allowedto access for the serving base station to perform interference alignmentprecoding.

According to another aspect of the present disclosure, a method foraccessing a spectrum in a communication system is provided. Thecommunication system includes a spectrum management apparatus, one ormore primary devices and one or more secondary devices. The methodincludes determining, by the spectrum management apparatus, at least onesecondary device which is allowed to access an idle portion of spectrumof the primary device based on position information and antenna angleinformation of each secondary device, in response to a request from thesecondary device for accessing the idle portion of spectrum; for each ofthe at least one secondary device which is allowed to access,transmitting, by the spectrum management apparatus, to a serving basestation serving the secondary device the position information and theantenna angle information of all of the at least one secondary deviceswhich is allowed to access; and performing, by the serving base station,interference alignment preceding on an actual transmission signal byusing the transmitted position information and antenna angleinformation, for transmission to the secondary device which is served bythe serving base station and allowed to access.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be better understood with reference to thefollowing description given in conjunction with the drawings, in whichsame or like reference numerals are used to denote the same or likecomponents throughout the drawings. The drawings, together with thedetailed description below, are incorporated in the specification andform a part of the specification, and are used to further illustratepreferred embodiments of the present disclosure and explain principlesand advantages of the present disclosure. In the drawings:

FIG. 1A and FIG. 1B are flowcharts schematically showing a process thata secondary device accesses an idle frequency band according to thepresent disclosure;

FIG. 2 is a flowchart showing a process that a spectrum coordinatordetermines secondary devices which are allowed to access an idlefrequency band according to a first embodiment;

FIG. 3 is a flowchart showing a process that a spectrum coordinatordetermines secondary devices which are allowed to access an idlefrequency band according to a second embodiment;

FIG. 4 shows a functional block diagram of a spectrum coordinatoraccording to the present disclosure; and

FIG. 5 is a block diagram, showing an example configuration of computerhardware.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1A and FIG. 1B are flowcharts showing a process of accessing anidle frequency band according to the present disclosure. As shown inFIG. 1A, a cognitive MIMO system according to the present disclosureincludes a spectrum coordinator 100, a base station PBS serving aprimary device, and multiple base nations SBS 1, SRS 2, . . . SBS sserving multiple secondary devices. Each of the multiple base stationsSBS 1 to SBS s may be. for example, a base station in a microcell or apicocell.

Firstly, in step S110, each of the base stations SBS 1 to SBS s acquiresposition information and antenna angle information of a secondary deviceserved by the base station, and then transmits the acquired positioninformation and the acquired antenna angle information of the secondarydevice to the spectrum coordinator 100. Optionally, in step S110, eachof the base stations SBS 1 to SBS s may farther report to the spectrumcoordinator 100 whether the secondary device has a capability ofsupporting interference alignment precoding.

In step S115, the base station PBS reports a communication performanceindicator (such as interference-to-noise ratio, INR) and antennainformation (such as the number of antennas, antenna angle, etc.) of theprimary device to the spectrum coordinator 100. Optionally, at stepS115, the base station PBS may further report position information andantenna angle information of the primary device to the spectrumcoordinator 100. Then, in step S120, the base station PBS reports to thespectrum coordinator 100 information indicating an idle portion ofspectrum available for access by the secondary device.

It is assumed that the secondary devices served by the base stations SBS1, SBS 2 and SBS s among the multiple base stations SBS 1 to SBS srequire to access the idle portion of spectrum of the primary device forperforming communication. Therefore, in step S130, each of the basestations SBS 1, SBS 2 and SBS s transmits a request message forrequesting to access the idle portion of spectrum to the spectrumcoordinator 100. It should be noted that, the above steps S110 to S130only schematically explain the process, and the present disclosure isnot limited to the order of performing the processes as described above.The above steps S110 to S130 may be performed in an order different fromthat shown in FIG. 1A.

Next, in step S140, the spectrum coordinator 100 determines, based onthe receded information on the secondary device and the primary device,whether to allow the secondary devices served by the base stations SBS1, SBS 2 and SBS s which transmit the request messages to access theidle portion of spectrum. The process of step S140 is described below indetail with reference to FIG. 2 and FIG. 3.

Reference is made to the flowchart shown in FIG. 1B after the secondarydevices which are allowed to access the idle portion of spectrum aredetermined. It is assumed in FIG. 1B that the spectrum coordinator 100allows only the secondary devices served by the base stations SBS 1 andSBS 2 to access the idle portion of spectrum. Therefore, in step S150,the spectrum coordinator 100 notifies each of the base stations SBS 1and SBS 2 of the position information and the antenna angle informationof all the secondary devices which are allowed to access as well asposition information and antenna angle information of other deviceswhich are interfered by the secondary devices served by thecorresponding base station and allowed to access.

As shown in step S100, upon the receipt of relevant information notifiedby the spectrum coordinator 100, each of the base stations SBS 1 and SBS2 calculates, based on the relevant information, a transmission channelmatrix and an interference channel matrix for the secondary device whichis served by the base station and allowed to access. Next, in step S170,each of the base stations SBS 1 and SBS 2 performs interferencealignment precoding on a transmission signal for the secondary devicewhich is served by the base station and allowed to access, and transmitsthe preceded signal to the secondary device which is served by the basestation and allowed to access.

A process (step S140 in FIG. 1A) that the spectrum coordinator 100determines secondary devices which are allowed to access an idlefrequency band according to a first embodiment is described below indetail with reference to FIG. 2. As shown in FIG. 2, in step S211, thespectrum coordinator 100 sets the maximum number Nth of secondarydevices which are allowed to access the idle portion of spectrum basedon information on the interference-to-noise ratio (INR) and the numberof antennas of the primary device reported by the base station PBS instep S115. Besides, the spectrum coordinator 100 sets a value Nsu of acounter representing the number of secondary devices which havecurrently accessed the idle portion of spectrum of the primary device to0.

Specifically, the report by the base station PBS in step S115 may beperiod with performed. Therefore, when the number of antennas or the INRof the primary device changes, the spectrum coordinator 100 may acquirethe change and reset, based on the change, the maximum number Nth ofsecondary devices which are allowed to access. In this way, a value ofthe parameter Nth may be dynamically set based on a change incommunication performance of the primary device. For example, in a casewhere the INR of the primary device is equal to 0 dB, it indicates thatan allowable amount of interference for the primary device is equal toan amount of noise. In addition, when the INR of the primary devicedecreases, it indicates that the allowable amount of interferencedecreases. In this case, the spectrum coordinator 100 may reset thevalue of the parameter Nth to a smaller value. That is, the spectrumcoordinator 100 may reduce the number of secondary devices which areallowed to access the idle portion of spectrum of the primary device,thereby reducing interference to the primary device from the secondarydevices. In addition, when the INR of the primary device increases, thespectrum coordinator 100 may increase the value of the parameter Nth.

In addition, as described above, each of the base stations SBS 1 to SBSs may further report to the spectrum coordinator 100 whether thesecondary device served by the base station has the capability ofsupporting interference alignment precoding in step S110. In this case,the spectrum coordinator 100 may set the maximum number Nth of secondarydevices which are allowed to access based on whether each secondarydevice has the capability. For example, since interference amongsecondary devices as well as interference between the secondary devicesand the primary device may be well suppressed by means of interferencealignment precoding, the spectrum coordinator 100 may set the maximumnumber Nth of secondary devices which are allowed to access to be agreater value in a case where the number of secondary devices supportinginterference alignment precoding in the system is larger. Otherwise, thevalue of the parameter Nth is set to be a smaller value.

As shown in step S212, the spectrum coordinator 100 enters into astand-in state after setting Nth and Nsu, that is, the spectrumcoordinator 100 waits to receive an access request from a secondarydevice. When receiving a request message for requesting to access theidle portion of spectrum from a specific secondary device in step S213,the spectrum coordinator 100 increases the value Nsu of the counter by 1in step S214. Next, in step S215 the spectrum coordinator 100 comparesthe increased value Nsu of the counter with the previously set maximumnumber Nth. If it is determined in step S215 that Nsu is greater thanNth, which indicates that the maximum number of the secondary devicesallowed to access the idle frequency band will be exceeded, and thus therequest from the secondary device is not approved, and the process isended. In addition, if it is determined in step S215 that Nsu is lessthan or equal to Nth, which indicates that the maximum number of thesecondary devices allowed to access will not be exceeded even when thespecific secondary device accesses the idle portion of spectrum, andthus the process proceeds to step S216.

In step S216, the spectrum coordinator 100 calculates, based on theacquired position information and the acquired antenna angle informationof each secondary acute (for example, in step S110 of FIG. 1A), atransmission channel matrix H_(jj) and an interference channel matrixH_(ij) for a secondary device (which is hereinafter referred to as aj-th secondary devices requesting access, where i, j=0,1, . . . , s, andi≠j. The transmission channel matrix H_(jj) indicates the communicationchannel between the j-th secondary device and a secondary devicecorresponding to the j-th secondary device at the other party, and theinterference channel matrix H_(ij) indicates the interference channelbetween the j-th secondary device and other secondary devices.Specifically, in the case where the base station PBS additionallyreports the position information and the antenna angle information ofthe primary device to the spectrum coordinator 100 in step S115, theinterference channel matrix H_(ij) calculated here may also indicate theinterference channel between the j-th secondary device and the primarydevice.

The spectrum coordinator 100 starts to evaluate reception performancefor the j-th secondary device requesting access in step S216 todetermine whether to allow the j-th secondary device to access the idlefrequency band based on the evaluation result. In general, the spectrumcoordinator 100 generates a transmission signal for evaluation, performsinterference alignment preceding on the transmission signal (i.e.,evaluation signal) and transmits the precoded signal, calculates thereception performance of the j-th secondary device with respect to thetransmission signal, and determines, based on the reception performance,whether to allow the j-th secondary device to access the idle portion ofspectrum, which will be described below in detail.

In step S217, the spectrum coordinator 100 calculates, based on thetransmission channel matrix. H_(jj) for the j-th secondary devicecalculated in step S216, a transmission signal-to-noise ratio (SNR) forthe j-th secondary device, which may be expressed as follows:

$\begin{matrix}{{SNR}_{j} = \frac{H_{jj}W_{j}W_{j}^{H}H_{jj}^{H}}{Z_{j}Z_{j}^{H}}} & (1)\end{matrix}$

where H_(jj) represents transmission channel matrix for the j-thsecondary device, W_(j) represents transmission beam forming matrix forthe j-th secondary device, and Z_(j) represents gaussian noise.

If the calculated signal-to-noise ratio SNR_(j) is less than a presetthreshold SNR_(th), which indicates that the communication performanceof the j-th secondary device is relatively poor, the spectrumcoordinator 100 rejects the access request from the secondary device asshown in step S218, and the process returns back to step S212 to be inthe stand-by state. It should be noted that, the preset thresholdSNR_(th) may be set by those skilled in the art according to actualdesign requirements, which is not described herein.

If the signal-to-noise ratio SNR, calculated in step S217 is greaterthan or equal to the preset threshold SNR_(th), the process proceeds tostep S219. In step S219, the spectrum coordinator 100 performsinterference alignment preceding on the evaluation signal to betransmitted to the j-th secondary device. An interference alignmentprecoding matrix to be used may be expressed as follows:

U _(0j)=null{H _(0j)}

U _(1j)=null{H _(1j) U _(0j)}

U _(sj)=null{H _(sj) U _((s−1)j) . . . U _(0j)}  (2)

where H_(0j) represents interference channel matrix from the j-thsecondary device to the 0-th secondary device, and so on, and H_(sj)represents interference channel matrix from the j-th secondary device tothe s-th secondary device. In addition, U_(0j) represents interferencealignment precoding matrix for the j-th secondary device with respect tothe 0-th secondary device, which is placed on the leftmost in theinterference alignment precoding, and so on, and U_(sj) representsinterference alignment precoding matrix for the j-th secondary devicewith respect to the s-th secondary device, which is placed on therightmost in the interference alignment precoding. By performing, withthe interference alignment preceding matrix U, interference alignmentprecoding on the transmission signal, (i.e., the evaluation signalgenerated by the spectrum coordinator 100) for the j-th secondary deviceand transmitting the precoded signal, the signal received by the j-thsecondary device may be acquired, which may be expressed as follows:

$\begin{matrix}\begin{matrix}{{\overset{\_}{y}}_{j} = {{\beta_{j}H_{jj}{\prod\limits_{{i = 1},{i \neq j}}^{s}{U_{ij}W_{j}x_{j}}}} + {\sum\limits_{{i = 1},{i \neq j}}^{s}\left( {\beta_{i}H_{ji}{\prod\limits_{{k = 0},{k \neq i}}^{s}{U_{ki}W_{i}x_{i}}}} \right)} + Z_{j}}} \\{= {{\beta_{j}H_{jj}{\prod\limits_{{i = 1},{i \neq j}}^{s}{U_{ij}W_{j}x_{j}}}} + Z_{j}}} \\{= {{{\hat{H}}_{jj}x_{j}} + Z_{j}}}\end{matrix} & (3)\end{matrix}$

where β_(j) represents transmission power control factor, and x_(j)represents transmission signal. Since interference alignment precedingis performed, the item of

${\sum\limits_{{i = 1},{i \neq j}}^{s}\left( {\beta_{i}H_{ji}{\prod\limits_{{k = 0},{k \neq i}}^{s}{U_{ki}W_{i}x_{i}}}} \right)} = 0$

in the expression (3) is 0, which represents mutual interference betweenthe j-th secondary device and other secondary devices. That is, mutualinterference among the secondary devices may be eliminated by means ofinterference alignment preceding.

Then, the spectrum coordinator 100 restores the evaluation signal fromthe reception signal y _(j) by zero-forcing equalization or minimum meansquare error (MMSE) criterion. The restored signal may be expressed asfollows:

$\begin{matrix}{{\overset{̑}{x}}_{j} = {{\hat{H}}_{jj}^{- 1}{\overset{\_}{y}}_{j}}} & (4)\end{matrix}$

Since the spectrum coordinator 100 generates the transmission signal forevaluation as described above, the spectrum coordinator 100 maydetermine, based on the transmission signal and the restored signal X_(j) shown in the mathematic expression (4), the reception performancefor the j-th secondary device, such as bit error rate (BER). Thereception performance indicates quality of signal received by the j-thsecondary device to a case that interference alignment preceding isperformed on the transmission signal for the j-th secondary device.

Then as shown in step S220, the spectrum coordinator 100 compares thedetermined bit error rate BER, with a preset threshold BER_(th). Thethreshold BER_(th) may be set by those skilled in the art according toactual design requirements which is not described herein. If BER_(j) isless than the threshold BER_(th), which indicates that the j-thsecondary device cannot achieve an acceptable quality of the receivedsignal even if interference alignment precoding is performed, thespectrum coordinate 100 does not allow the j-th secondary device toaccess the idle portion of spectrum, and the process proceeds to stepS218. In addition, if BER_(j) is greater than or equal to the thresholdBER_(th), which indicates that interference among the secondary devicescan be beneficially suppressed by means of interference alignmentprecoding and the j-th secondary device can achieve a relatively goodreception performance, the spectrum coordinator 100 allows the j-thsecondary device to access the idle portion of spectrum as shown in stepS221, and the process returns back to S212 to be in the stand-by stateagain.

It should be noted that step S217 is optional in the process shown inFIG. 2. That is, the step of comparing the signal-to-noise ratios (SNRs)may be omitted. In this case, the spectrum coordinator 100 performs theinterference alignment precoding process in step S219 immediately aftercalculating the transmission channel matrix and the interference channelmatrix in step S210.

A process (step S140 in FIG. 1A) that the spectrum coordinator 100determines secondary devices which are allowed to access an idlefrequency band according to a second embodiment is described below indetail with reference to FIG. 3. The process differs from the processaccording to the first embodiment shown in FUG, 2 in that a situationwhere the secondary devices have different priorities is considered.

As shown in FIG. 3, in step S311 which is similar to step S211 in FIG.2, the spectrum coordinator 100 sets the maximum number Nth of secondarydevices which are allowed to access the idle portion of spectrum, andsets a value Nsu of a counter representing the number of secondarydevices which have currently accessed the idle portion of spectrum to 0.In addition, in step S311, the spectrum coordinator 100 furtherdetermines the initial lowest priority α_(s) of the secondary devices inthe system.

Then, in step S312, the spectrum coordinator 100 waits to receive anaccess request from a secondary device. In step S313, the spectrumcoordinator 100 receives a request message for requesting to access theidle portion of spectrum from the j-th secondary device with priorityα_(j). Next, the spectrum coordinator 100 increases the value Nsu of thecounter by 1 in step S314, and compares the priority α_(j) of the j-thsecondary device with the lowest priority α_(s) in step S315.

If the priority α_(j) of the j-th secondary device is greater than thelowest priority α_(s) in the system, which indicates that the secondarydevice requesting access has a higher priority, the spectrum coordinator100 allows the j-th secondary device to access the idle portion ofspectrum as shown in step S316. In this case, in step S317, the spectrumcoordinator 100 compares the current value Nsu of the counter with themaximum number Nth of the secondary devices allowed to access. If Nsu isless than Nth, which indicates that the maximum number of the secondarydevices allowed to access has not been reached, that is, an additionalaccess is still possible, the process returns back to the step S312 tobe in the stand-by state. If Nsu is greater than Nth, it indicates thatthe number of secondary devices accessing the idle portion of spectrumafter allowing the j-th secondary device to access in step S316 willexceed the maximum number of the secondary devices allowed to access. Inthis case, the spectrum coordinator 100 terminates usage of the idleportion of spectrum, by the secondary device with the lowest priorityα_(s) in step S318, and updates the lowest priority α_(s) in the systemin step S319 after the termination operation. In addition, if thecurrent value Nsu of the counter is equal to Nth the process alsoreturns back to step S312 to be in the stand-by state, that is, thespectrum coordinator 100 waits to receive an access request from thenext secondary device, which is the same as the case in which Nsu isless than Nth.

Referring back to step S315, if the priority α_(j) of the j-th secondarydevice is equal to or less than the lowest priority α_(s) in the system,it is further determined whether the current value of the counter Nsu isgreater than the maximum number Nth of the secondary devices allowed toaccess, as shown in step S320.

If it is determined in step S320 that Nsu is greater than Nth, the j-thsecondary device is not allowed to access the idle portion of spectrum,as shown in step S321.

If it is determined in step S320 that Nsu is less than or equal to Nth,the process proceeds to step S322, that is, the spectrum coordinator ioncalculates, based on the acquired position information of each secondarydevice, a transmission channel matrix H_(jj) and an interference channelmatrix H_(ij) for the j-th secondary device. Next, the spectrumcoordinator 100 performs steps S323 to S326. The steps S323, S324, S325and S326 are the same as steps S217, S219, S220 and S221 shown in FIG.2, respectively, which are not repeated herein. It should be noted thatthe process of comparing the signal-to-noise ration (SNRs) in step S323herein is also optional, which is similar to step S217 in FIG. 2.

Specifically, after allowing the j-th secondary device to access theidle portion of spectrum in step S326, the spectrum coordinator 100needs to predetermine the lowest priority α_(s) of the secondary devicesin the system, and the process proceeds to step S319. Next, the spectrumcoordinator 100 returns back to step S312 to be in the stand-by state,waiting for an access request from the next secondary device.

It should be noted that, although the process of controlling accessbused on a priority of a secondary device is mainly described, theprocess may also be performed based on the desired QoS level of thesecondary device. The level of QoS corresponds to the level of priority.

Functional modules of the spectrum coordinator 100 according to thepresent disclosure are described below with reference to FIG. 4. Asshown in FIG. 4, the spectrum coordinator 100 includes an informationdetermination unit 410, an interference alignment precoding matrixcalculation unit 420, an evaluation signal generation unit 430, anevaluation unit 440, a permission unit 450, and a maximum access numbersetting unit 460. The functional modules are described below one by one.

The information determination unit 410 determines, based on informationreported by base stations SBS 1 to SBS s and PBS, information of eachsecondary device and a primary device, such as information on the numberof antennas. Information on antenna angle, position information,communication performance information, information on whetherinterference alignment precoding is supported, and provides thedetermined information to the interference alignment precoding matrixcalculation unit 420 and the maximum access number setting unit 460.

The interference alignment precoding matrix calculation unit 420calculates, based on the relevant information on the secondary deviceand the primary device provided by the information determination unit410, an interference channel matrix between a specific secondary deviceand other secondary devices and/or the primary device, and generates aninterference alignment precoding matrix for the specific secondarydevice based on the calculated interference channel matrix, as shown inthe mathematic expression (2).

The evaluation signal generation unit 430 generates an evaluation signalwhich is assumed to be transmuted to the specific secondary device forevaluating reception performance of the specific secondary device withrespect to the evaluation signal.

The evaluation unit 440 receives the generated interference alignmentprecoding matrix and the evaluation signal from the interferencealignment precoding matrix calculation unit 420 and the evaluationsignal generation unit 430, respectively, and performs preceding on theevaluation signal by using the interference alignment precoding matrix,to acquire a signal that may be received by the specific secondarydevice, as shown in the mathematic expression (3). The evaluation unit440 restores the evaluation signal from the acquired reception signaland determines the reception performance (such as BER) for theevaluation signal by comparing the restored signal with the originalevaluation signal. Then, the evaluation unit 440 provides the determinedreception performance to the permission unit 450 as the evaluationresult.

The permission unit 450 determines whether to allow the specificsecondary device to access the idle portion of spectrum of the primarydevice based an the evaluation result. In addition to the receptionperformance, the permission unit 450 may also determine whether to allowthe specific secondary device to access the idle portion of spectrumbased on the priority (or QoS level) of the specific secondary device,or the maximum number of secondary devices which are allowed to access,and the like.

The maximum access number setting unit 460 sets, based on antennainformation and communication performance information of the primarydevice and/or the capability of supporting interference alignmentprecoding of the secondary device provided by the informationdetermination unit 410, the maximum number of secondary devices whichare allowed to access the idle portion of spectrum, and provides themaximum number to the permission unit 450, so that the permission unit450 may operate based on the maximum number.

Various embodiments of the present disclosure have been described abovein detail in conjunction with the drawings. According to the presentdisclosure, the spectrum coordinator controls access of the secondarydevices, so as to select an optimal combination of secondary devices toaccess a spectrum of the primary device, thereby ensuring a bettercommunication performance for a cognitive device which accesses thespectrum compared to a case where spectrum access is not limited(uncontrolled), and improving utility efficiency of spectrums and systemcapacity.

In addition according to the present disclosure, for the secondarydevices requesting access to the spectrum, the spectrum coordinatoreffectively coordinates the orderly access of the secondary devices,therein efficiently responding to frequent changes in network status inreal time. In addition information (such as position information andantenna angle information) is exchanged only at base station side, sothat the usage of pilot can be reduced, thereby reducing system energyconsumption and pilot pollution. In addition, the present disclosureprovides processes for a case in which the secondary devices havedifferent priorities or QoSs, thereby meeting different QoS requirementsof the secondary devices.

The base station described in the present disclosure may be implementedas any type of evolved node B (eNB), such as macro eNB and small eNB.The small eNB may be an eNB covering a cell smaller than a macro cell,such as pico eNB, micro eNB and home (femto) eNB. Alternatively, thebase station may also be implemented as any other type of base stations,such as NodeB and base transceiver station (BTS). Various types ofterminals each may operate as a base station by temporarily orsemi-persistently performing functions of the base station. The basestation may include a main body (also referred to as a base stationdevice) configured to control wireless communication; and one or moreremote radio heads provided separately from the main body.

The order of the steps described herein is merely illustrative, and theorder in which the process or the flow is performed is not limitedthereto. Without affecting the implementation of the present disclosure,the order of the steps may be changed, or some steps may be performed inparallel with other steps.

It should further be noted that various devices or components describedherein are merely logical in nature and do not strictly correspond tophysical devices of components. For example, the functionality of eachcomponent described herein may be implemented by multiple physicalentities, or the functionality of multiple components described hereinmay be implemented by a single physical entity.

The series of processes executed by each device or component in theembodiments may be implemented by software, hardware, or a combinationof software and hardware. Programs included in the software may bestored in advance in a storage medium provided inside or outside eachdevice or component. As an example, during execution, these programs arewritten to a random access memory (RAM) and executed by a processor(such as CPU).

FIG. 5 is a block diagram showing an example configuration of computerhardware that executes the above processes according to a program.

In computer 500, central processing unit (CPU) 501, read only memory(ROM) 502, and random access memory (RAM) 503 are connected to eachother via bus 504.

An input/output interface 505 is further connected to the bus 504. Theinput/output interface 505 is connected with the following components:an input unit 506 including keyboard, mouse, microphone, and the like;an output unit 507 including display, speaker and the like; storage unit508 including hard disk, nonvolatile memory or the like; communicationunit 509 including network interface card (such as local area network(LAN) card, modem), and drive 510 that drives removable medium 511 suchas magnetic disk, optical disk, magneto-optical disk, or semiconductormemory.

In the computer having the above configuration, the CPU 501 loads aprogram stored in the storage unit 508 into the RAM 503 via the inputoutput interface 505 and the bus 504, and executes the program so as toexecute the above processes.

The program to be executed by the computer (CPU 501) may be recorded onthe removable medium 511 which is a package medium formed by for examplemagneto disk (including floppy disk), optical disk (including compactdisk-read only memory (CD-ROM)), digital versatile disk (DVD), and thelike), magneto-optical disk, or semiconductor memory, and the like inaddition the program to be executed by the computer (CPU 501) may alsobe provided via a wired or wireless transmission medium such as a localarea network the Internet, or digital satellite broadcast.

In a case where the removable medium is installed in the drive 510, theprogram may be installed in the storage unit 508 via the input/outputinterface 505. In addition, the program may be received by thecommunication unit 509 via a wired or wireless transmission medium, andthen the program may be installed in the storage unit 508.Alternatively, the program may be installed in the ROM or the storageunit 508 in advance.

The program to be executed by the computer may be a program thatexecutes the processes according to the order described in the presentspecification or may be a program that executes the processes inparallel or executes the processes when needed (for example, whencalled).

The embodiments an the technical effects of the present disclosure havebeen described above in detail in conjunction with the drawings, but thescope of the present disclosure is not limited thereto. It should beunderstood by those skill in the art that various modifications orchanges in the embodiments discussed herein can be made withoutdeparting from the spirit and principle of the present disclosure,depending on design requirements and other factors. The scope of thepresent disclosure is defined by the appended claims or theirequivalents.

In addition, the present disclosure may also be configured, as follows.

A spectrum management apparatus, including one or more processorsconfigured to: determine position information and antenna angleinformation of each of one or more secondary devices; determine at leastone secondary device which is allowed to access an idle, portion ofspectrum of a primary device based on the position information and theantenna angle information of each secondary device, in response to arequest from the secondary device for accessing the idle portion ofspectrum; and for each of the at least one secondary device which isallowed to access, transmit to a serving base station serving thesecondary device the position information and the antenna angleinformation of all of the at least one secondary device which is allowedto access for the serving base station to perform interference alignmentpreceding.

The one or more processors may further be configured to: determineantenna information and communication performance information of theprimary device, and set a maximum number of the secondary devices whichare allowed to access the idle portion of spectrum based on thedetermined antenna information and communication performanceinformation; determine a transmission channel matrix and an interferencechannel matrix for the secondary device requesting access to the idleportion of spectrum based on the position information and the antennaangle information of each secondary device; determine receptionperformance of the secondary device requesting access based on thetransmission channel matrix and the interference channel matrix; anddetermine whether to allow the secondary device requesting access toaccess the idle portion of spectrum based on the reception performanceand the maximum number of the secondary devices which are allowed toaccess the idle portion of spectrum.

The one or more processors may further be configured to determineposition information and antenna angle information of the primarydevice; and determine the interference channel matrix for the secondarydevice requesting access based on the position information and theantenna angle information of the primary device.

The one or more processors may further be configured to: generate anevaluation signal; determine an interference alignment precoding matrixfor the secondary device requesting access by using the determinedinterference channel matrix; and determine the reception performance ofthe secondary device requesting access with respect to the evaluationsignal at a case where interference alignment precoding has beenperformed on the evaluation signal by using the interference alignmentprecoding matrix.

The one or more processors may further be configured to: determine areception signal obtained through receiving the evaluation signal by thesecondary device requesting access, and restore the evaluation signalfrom the reception signal; and evaluate the reception performance basedon the restored signal and the evaluation signal.

The one or more processors may further be configured to: determine anerror rate of the restored signal; and allow the secondary devicerequesting access to access the idle portion of spectrum in a case wherethe error rate is less than a first threshold.

The one or more processors may further be configured to: determine asignal-to-noise ratio for the secondary device requesting access byusing the determined transmission channel matrix; and determine thereception performance of the secondary device requesting access in acase where the signal-to-noise ratio is greater than a second threshold.

The one or more processors may further be configured to: set dynamicallythe maximum number of the secondary devices which are allowed to accessthe idle portion of spectrum based on a change in the antennainformation and the communication performance information of the primarydevice.

The secondary devices may have different priorities, and the one or moreprocessors may further be configured to: compare the priority of thesecondary device requesting access with the lowest one of the prioritiesof the secondary devices which have accessed the idle portion ofspectrum; and determine whether to allow the secondary device requestingaccess to access the idle portion of spectrum based on a result ofcomparison.

The one or more processors may further be configured to: allow thesecondary device requesting access to access the idle portion ofspectrum in a case where the priority of the secondary device requestingaccess is greater than the lowest priority.

The one or more processors may further be configured to: forbid asecondary device with the lowest priority to use the idle portion ofspectrum if a number of the secondary devices which are currentlyallowed to access the idle portion of spectrum is greater than themaximum number, in a case where the secondary device requesting accessis allowed to access the idle portion of spectrum.

The one or more processors may further be configured to: determinewhether to allow the secondary device requesting access to access theidle portion of spectrum based on a number of the secondary deviceswhich have accessed the idle portion of spectrum, in a case where thepriority of the secondary device requesting access is less than or equalto the lowest priority.

The one or more processors may further be configured to: forbid thesecondary device requesting access to access the idle portion ofspectrum in a case where the number of the secondary devices which haveaccessed the idle portion of spectrum reaches to the maximum number; anddetermine the reception performance of the secondary device requestingaccess in a case where the number of the secondary devices which haveaccessed the idle portion of spectrum has not reached to the maximumnumber.

A method for controlling: spectrum access in a communication system,including: determining position information and antenna angleinformation of each of one or more secondary devices; determining atleast one secondary device which is allowed to access an idle portion ofspectrum of a primary device based on the position information and theantenna angle information of each secondary device, in response to arequest from the secondary device for accessing the idle portion ofspectrum; and for each of the at least one secondary device which isallowed to access, transmitting to a serving base station serving thesecondary device the position information and the antenna angleinformation of all of the at least one secondary device which is allowedto access for the serving base station to perform interference alignmentprecoding.

The method may further include: determining antenna information andcommunication performance information of the primary device, and settinga maximum number of the secondary devices which are allowed to accessthe idle portion of spectrum based on the determined antenna informationand communication performance information; determining a transmissionchannel matrix and an interference channel matrix for the secondarydevice requesting access to the idle portion of spectrum based on theposition information and the antenna angle information of each secondarydevice; determining reception performance of the secondary devicerequesting access based on the transmission channel matrix and theinterference channel matrix; and determining whether to allow thesecondary device requesting access to access the idle portion ofspectrum based on the reception performance and the maximum number ofthe secondary devices which are allowed to access the idle portion ofspectrum.

The method may further include generating an evaluation signaldetermining an interference alignment precoding matrix for the secondarydevice requesting access by using the determined interference channelmatrix, and determining the reception performance of the secondarydevice requesting access with respect to the evaluation signal in a casewhere interference alignment preceding has been performed on theevaluation signal by using the interference alignment precoding matrix.

The method may further include: determining a reception signal obtainedthrough receiving the evaluation signal by the secondary devicerequesting access, and restoring the evaluation signal from thereception signal; and evaluating the reception performance based on therestored signal and the evaluation signal.

The secondary devices may have different priorities, and the method mayfurther include: comparing the priority of the secondary devicerequesting access with the lowest one of the priorities of the secondarydevices which have accessed the idle portion of spectrum; anddetermining whether to allow the secondary device requesting access toaccess the idle portion of spectrum based on a result of comparison.

The method may further include: allowing the secondary device requestingaccess to access the idle portion of spectrum in a case where thepriority of the secondary device requesting access is greater than thelowest priority.

The method may further include: determining whether to allow thesecondary device requesting access to access the idle portion ofspectrum based on a number of the secondary devices which have accessedthe idle portion of spectrum, in a case where the priority of thesecondary device requesting access is less than or equal to the lowestpriority.

A method for accessing a spectrum in a communication system, where thecommunication system includes a spectrum management apparatus, one ormore primary devices and one or more secondary devices, and the methodincludes: determining, by the spectrum management apparatus, at leastone secondary device which is allowed to access an idle portion ofspectrum of the primary device based on position information and antennaangle information of each secondary device, in response to a requestfrom the secondary device for accessing the idle portion of spectrum foreach of the at least out secondary device which is allowed to accesstransmitting, by the spectrum management apparatus, to a serving basestation serving the secondary device the position information and theantenna angle information of all of the at least one secondary devicewhich is allowed to access, and performing, by the serving base station,interference alignment precoding on an actual transmission signal byusing the transmuted position information and antenna angle information,for transmission to the secondary device which is served by the servingbase station and allowed to access.

The step of the determining the secondary devices which are allowed toaccess the idle portion of spectrum may further include: determiningantenna information and communication performance information of theprimary device, and setting a maximum number of the secondary deviceswhich are allowed to access the idle portion of spectrum based on thedetermined antenna information and communication performanceinformation. determining a transmission channel matrix and aninterference channel matrix for the secondary device requesting accessto the idle portion of spectrum based on the position information andthe antenna angle information of each secondary device; determiningreception performance of the secondary device requesting access based onthe transmission channel matrix and the interference channel matrix; anddetermining whether to allow the secondary device requesting access toaccess the idle portion of spectrum based on the reception performanceand the maximum number of the secondary devices which are allowed toaccess the idle portion of spectrum.

The step of the determining the reception performance of the secondarydevice requesting access may further include: generating an evaluationsignal, determining an interference alignment precoding matrix for thesecondary device requesting access by using the determined interferencechannel matrix; and determining the reception performance of thesecondary device requesting access with respect to the evaluation signalin a case where interference alignment precoding has been performed onthe evaluation signal by using the interference alignment precodingmatrix.

The step of the determining the reception performance of the secondarydevice requesting access with respect to the evaluation signal mayfurther include: determining a reception signal obtained throughreceiving the evaluation signal by the secondary device requestingaccess, and restoring the evaluation signal from the reception signal;and evaluating the reception performance based on the restored signaland the evaluation signal.

The secondary devices may have different priorities and the method mayfurther include: comparing, by the spectrum management apparatus, thepriority of the secondary device requesting access with the lowest oneof the priorities of the secondary devices which have accessed the idleportion of spectrum; and determining by the spectrum managementapparatus, whether to allow the secondary device requesting access toaccess the idle portion of spectrum based on a result of comparison.

The method may further include: allowing, by the spectrum managementapparatus, the secondary device requesting access to access the idleportion of spectrum in a case where the priority of the secondary devicerequesting access is greater than the lowest priority; and determining,by the spectrum management apparatus, whether to allow the secondarydevice requesting access to access the idle portion of spectrum based ona number of the secondary devices which have accessed the idle portionof spectrum, in a case where the priority of the secondary devicerequesting access is less than or equal to the lowest priority.

1. A spectrum management apparatus, comprising one or more processorsconfigured to: determine position information and antenna angleinformation of secondary devices; determine at least one secondarydevice which is allowed to access an idle portion of spectrum of aprimary device based on the position information and the antenna angleinformation of secondary device, in response to a request from thesecondary device for accessing the idle portion of spectrum; and for thesecondary device which is allowed to access, transmit to a serving basestation, the position information and the antenna angle information ofthe secondary device which is allowed to access to perform interferencealignment precoding.
 2. The spectrum management apparatus according toclaim 1, wherein the one or more processors are further configured to:determine antenna information and communication performance informationof the primary device, and set a maximum number of the secondary deviceswhich are allowed to access the idle portion of spectrum based on thedetermined antenna information and communication performanceinformation; determine a transmission channel matrix and an interferencechannel matrix for the secondary device based on the positioninformation and the antenna angle information of each secondary device:determine reception performance of the secondary device requestingaccess based on the transmission channel matrix and the interferencechannel matrix; and determine whether to allow the secondary device toaccess the idle portion of spectrum, based on the reception performanceand the maximum number of the secondary devices.
 3. The spectrummanagement apparatus according to claim 2, wherein the one or moreprocessors are further configured to: determine position information andantenna angle information of the primary device; and determine theinterference channel matrix for the secondary device requesting accessbased on the position information and the antenna angle information ofthe primary device.
 4. The spectrum management apparatus according toclaim 2, wherein the one or more processors are further configured to:generate an evaluation signal; determine an interference alignmentprecoding matrix for the secondary device requesting access by using thedetermined interference channel matrix; and determine the receptionperformance: of the secondary device requesting access with respect tothe evaluation signal in a case where interference alignment precodinghas been performed on the evaluation signal by using the interferencealignment precoding matrix.
 5. The spectrum management apparatusaccording to claim 4, wherein the one or more processors are furtherconfigured to: determine a reception signal obtained through receivingthe evaluation signal by the secondary device requesting access, andrestore the evaluation signal from the reception signal; and evaluatethe reception performance based on the restored signal and theevaluation signal.
 6. The spectrum management apparatus according toclaim 5, wherein the one or more processors are further configured to:determine an error rate of the restored signal; and allow the secondarydevice requesting access to access the idle portion of spectrum in acase where the error rate is less than a first threshold.
 7. Thespectrum management apparatus according to claim 1, wherein the one ormore processors are further configured to: determine a signal-to-noiseratio for the secondary device requesting access by using the determinedtransmission channel matrix; and determine the reception performance ofthe secondary device requesting access in a case where thesignal-to-noise ratio is greater than a second threshold.
 8. Thespectrum management apparatus according to claim 2, wherein the one ormore processors are further configured to: set the maximum number of thesecondary devices which are allowed to access the idle portion ofspectrum based on a change in the antenna information and thecommunication performance information of the primary device.
 9. Thespectrum as management apparatus according to claim 2, wherein thesecondary devices base different priorities, and the one or moreprocessors are further configured to: compare the priority of thesecondary device requesting access with the lowest one of the prioritiesof the secondary devices which have accessed the idle portion ofspectrum; and determine whether to allow the secondary device requestingaccess to access the idle portion of spectrum based on a result ofcomparison; allow the secondary device requesting access to access theidle portion of spectrum in a case where the priority of the secondarydevice requesting access is greater than the lowest priority. 10.(canceled)
 11. The spectrum management apparatus according to claim 9,wherein the one or more processors are further configured to: forbid thesecondary device with the lowest priority to use the idle portion ofspectrum if a number of the secondary devices which are currentlyallowed to access the idle portion of spectrum is greater than themaximum number, in a case where the secondary device requesting accessis allowed to access the idle portion of spectrum.
 12. The spectrummanagement apparatus according to claim 9, wherein the one or moreprocessors are further configured to: determine whether to allow thesecondary device requesting access to access the idle portion ofspectrum based on a number of the secondary devices which have accessedthe idle portion of spectrum, in a case where the priority of thesecondary device requesting access is less than or equal to the lowestpriority.
 13. The spectrum management apparatus according to claim 12,wherein the one or more processors are further configured to: forbid thesecondary device requesting access to access the idle portion ofspectrum in a case where the number of the secondary devices which haveaccessed the idle portion of spectrum reaches to the maximum number; anddetermine the reception performance of the secondary device requestingaccess in a case where the number of the secondary devices which haveaccessed the idle portion of spectrum has not reached to the maximumnumber.
 14. A method for controlling spectrum access in a communicationsystem, comprising: determining position information and antenna angleinformation of each of one or more secondary devices: determining atleast one secondary device which is allowed to access an idle portion ofspectrum of a primary device based on the position information and theantenna angle information of each secondary device, in response to arequest from the secondary device for accessing the idle portion ofspectrum; and for each of the at least one secondary device which isallowed to access, transmitting to a serving base station serving thesecondary device the position information, and the antenna angleinformation of all of the at least one secondary device which is allowedto access for the serving base station to perform interference alignmentprecoding.
 15. The method, according to claim 14, further comprising:determining antenna information and communication performanceinformation of the primary device, and setting a maximum number of thesecondary devices which are allowed to access the idle portion ofspectrum based on the determined antenna information and communicationperformance information; determining a transmission channel matrix andan interference channel matrix for the secondary device requestingaccess to the idle portion of spectrum based on the position informationand the antenna angle information of each secondary device; determiningreception performance of the secondary device requesting access based onthe transmission channel matrix and the interference channel matrix; anddetermining whether to allow the secondary device requesting access toaccess the idle portion of spectrum based on the reception performanceand the maximum number of the secondary devices which are allowed toaccess the idle portion of spectrum.
 16. The method according to claim15, further comprising: generating an evaluation signal; determining aninterference alignment precoding matrix for the secondary devicerequesting access by using the determined interference channel matrix;and determining the reception performance of the secondary devicerequesting access with respect to the evaluation signal in a case whereinterference alignment precoding has been performed on the evaluationsignal by using the interference alignment precoding matrix.
 17. Themethod, according to claim 16, further comprising: determining areception signal obtained through receiving the evaluation signal by thesecondary device requesting access, and restoring the evaluation signalfrom the reception signal; and evaluating the reception performancebased on the restored signal and the evaluation signal.
 18. The methodaccording to claim 15, wherein the secondary devices have differentpriorities, and the method further comprises: comparing the priority ofthe secondary device requesting access with the lowest one of thepriorities of the secondary devices which have accessed the idle portionof spectrum; and determining whether to allow the secondary devicerequesting access to access the idle portion of spectrum based on aresult of comparison.
 19. The method according to claim 18, furthercomprising; allowing the secondary device requesting access to accessthe idle portion of spectrum in a case where the priority of thesecondary device requesting access is greater than the lowest priority.20. The method according to claim 18, further comprising: determiningwhether to allow the secondary device requesting access to access theidle portion of spectrum based on a number of the secondary deviceswhich have accessed the idle portion of spectrum, in a case where thepriority of the secondary device requesting access is less than or equalto the lowest priority. 21-26. (canceled)